Process for producing substitute for lithographic stones or metal plates.



' roughened or grained plate TINT n srar -HANS CHRISTENSEN, OF HALLE, GERMANY.

PROCESS FOR PRODUCING SUBSTITUTES FOR LITHOGRAIPHIC STONES OR METAE PLATES.

No Drawing.

Specification of Letters Patent.

Application filed July 21, 1909. Serial No. 508,859.

Patented May 2, 1911.

To all whom it may concern:

Be it known that I, HANs CHRISTENSEN, of Halle, Germany, have invented new and useful Improvements in Processes for Producing Substitutes for Lithographic'Stones or Metal Plates, of which the following is a specification.

The invention relates to the production of a substitute for natural lithographic stones and consists in applying to a backing a coating which serves as the printin surface. A ormed from stone, sheet zinc, or other metal is heated to a temperature of 90 (1, then suitably treat ed by means of an atomizer with a solution formed by adding sodium aluminate A.l(ONa) or a mixture of sodium hydrate NaOH and-aluminium hydrate Al(OH) to water saturated with carbon dioxid C0 The action of the carbon dioxid on the sodium aluminate solution is expressed by the following equation 2Al(ONa +3H O+3CO The carbon dioxid isnot supplied in sulfibe decomposed, but in such proportion that a portion remains undecomposed in the liquid so that the liquid used for spraying on the plates is finally of the following character:

The separated aluminium hydroxid is allowed. to settle, the solution applied to the hot plate is allowed to evaporate and the plate washed. The sodium aluminate is surrounded by carbon dioxid during the electrical chemical process. This method of coating, drying, and washing the plate is repeated several times until the coating ing the plate.

HANS CHRISTENSEN. Witnesses:

RUDOLPH FRICKE,

J. CHRISTENSEN. 

